Objectives

To evaluate the impact of aspirin resistance on the incidence of preeclampsia and maternal serum biomarker levels in pregnant individuals at high-risk of preeclampsia receiving low dose aspirin (LDA).

Study design

We performed a secondary analysis of a randomized, placebo-controlled trial of LDA (60 mg daily) for preeclampsia prevention in high-risk individuals (N = 524) on pregnancy outcomes and concentrations of PLGF, IL-2, IL-6, thromboxane B2 (TXB₂), sTNF-R1 and sTNF-R2 from maternal serum.

Main outcome measures

LDA-resistant individuals were defined as those having a TXB₂ concentration >10 ng/ml or <75 % reduction in concentration at 24-28 weeks after LDA administration. Comparisons of outcomes were performed using a Fisher's Exact Test. Mean concentrations of maternal serum biomarkers were compared using a Student's t-test. Pearson correlation was calculated for all pairwise biomarkers. Longitudinal analysis across gestation was performed using linear mixed-effects models accounting for repeated measures and including BMI and maternal age as covariates.

Results

We classified 60/271 (22.1 %) individuals as LDA-resistant, 179/271 (66.1 %) as LDA-sensitive, and 32/271 (11.8 %) as non-adherent. The prevalence of preeclampsia was not significantly different between the LDA and placebo groups (OR = 1.43 (0.99-2.28), p-value = 0.12) nor between LDA-sensitive and LDA-resistant individuals (OR = 1.27 (0.61-2.8), p-value = 0.60). Mean maternal serum IL-2 concentrations were significantly lower in LDA-resistant individuals relative to LDA-sensitive individuals (FDR < 0.05).

Conclusions

These results suggest a potential role for IL-2 in the development of preeclampsia modulated by an individuals' response to aspirin, presenting an opportunity to optimize aspirin prophylaxis on an individual level to reduce the incidence of preeclampsia.